The present invention relates to a method for manufacturing leaf springs from a fiber-composite material.
Leaf springs made from a fiber-composite material are increasingly replacing conventional leaf springs made from steel, since the former are, above all, lighter than the latter. When the former are used in a vehicle, said vehicle is altogether lighter, such that less energy has to be invested for driving said vehicle. This not only results in lower fuel consumption, but also in correspondingly reduced emissions of pollutants of the vehicle engine. However, leaf springs from a fiber-composite material have until now still been more expensive in their manufacture than comparable leaf springs from steel, such that the latter presently have a certain competitive advantage, particularly in the case of lower-value vehicles. The manufacturing costs for a fiber-composite leaf spring in comparison with those of a steel leaf spring which in its properties is comparable with the former are higher above all because fiber-composite material leaf springs presently used in the construction of vehicles are manufactured in a comparatively labor-intensive method. In this method, initially a leaf-spring blank is constructed by layering individual layers of prepregs on top of one another. Such prepreg layers are composed of a plurality of individual fiber strands, fiber cross-laid structures and/or fibrous woven fabrics, which are embedded in a yet non-cured duroplastic resin. The fibers may be configured as glass fibers, carbon fibers, or aramid fibers, for example. Subsequently, the initially still flexible leaf-spring blank is laid up in a compressive mold and cured at a predetermined temperature and pressure profile.
Such a method is disclosed, for example, in DE 10 2010 050 065 A1. The method of production which is described relates to the use of glass reinforced plastic materials for leaf springs. More specifically, fibers of different lengths are arranged one above the other and moistened with a synthetic resin. This method is indeed considered as being advantageous with respect to the properties of a fiber-composite material leaf spring which is manufacturable in this manner, but it does not have the effect of any significant reduction of the manufacturing costs of leaf springs from fiber-composite materials.